This invention relates to a hydraulic torque impulse tool primarily intended for applying torque to threaded joint parts, like screws and nuts.
In particular, the invention is related to a torque impulse tool in which the continuous torque output of a rotation motor is converted into torque impulses of a high peak magnitude. An inertia drive member rotatably supported in a housing is drivingly connected to a rotation motor and comprises a fluid chamber into which the rear end of an output spindle extends.
In previous impulse tools of this type, for example the tool described in U.S. Pat. No. 3,116,617, the inertia drive member is formed with a cylindrical fluid chamber which is disposed eccentrically in relation to the rotation axis of the inertia drive member. The rear end portion of the output spindle of this known device carries a radially displaceable blade the purpose of which is to maintain sealing contact with the wall of the eccentric fluid chamber as the inertia drive member is rotated relative to the output spindle. During a short interval of this relative rotation, a seal portion on the spindle, diametrically opposite to the moving blade, comes into sealing cooperation with a seal land on the chamber wall, whereby a rapid pressure build-up occurs on one side of the radial blade and a torque impulse is imposed on the output spindle.
This known type of hydraulic torque impulse tool has never gained any success among the users of torque delivering tools. This is mainly because of its undesirably low power-to-weight ratio.
In order to compensate for a poor impulse generating efficiency, the size of the impulse mechanism has been increased, whereby inevitably the weight and outer dimensions of the tool are increased too. This means that when a tool of the previously known type is adapted to todays performance requirements it would be far too heavy to meet todays demands as regards comfortable tool handling.
The primary object of the invention is to create an improved hydraulic torque impulse tool by which the power-to-weight ratio is substantially increased.
Further advantages and significant features of the invention will be apparent from the following description and drawings.